It has been known that hydrocarbon material and the like derived from gasoline or engine oil is deposited on internal parts of a gasoline engine so that the accelerating power of the engine decreases and the fuel economy decreases. Therefore, a detergent is added to the gasoline to remove the deposit. However, the addition of a detergent to gasoline is typically not enough for effectively removing the deposit. Therefore, the engine is generally disassembled at predetermined intervals and the internal parts of the engine are cleaned.
WO 03/062626 A1, discloses an apparatus for supplying a detergent liquid (a detergent composition) for removing deposit from the internal parts of engines. The apparatus is equipped with a treatment manifold having ports (orifices) for supplying the detergent liquid. In the use of the apparatus, the pipes of the manifold are inserted in the engine through the intake pipe so that the detergent liquid is supplied into positions in the vicinity of the deposits. Therefore, the deposits particularly formed on the intake valves of the engine are efficiently removed. The publication further discloses that nozzles can be attached to the ports of the pipes of the manifold so that the detergent liquid can be sprayed into the engine.
The apparatus disclosed in the WO 03/062626 A1 can efficiently remove deposits formed on the internal parts of an engine. However, it is not easy to adjust the number of the manifold pipes and their shapes in consideration of the structure of the engine to be cleaned so as to facilitate the operation for inserting the pipes of the manifold deeply in the intake pipe so that the ports of the pipes can be placed in the engine in the vicinity of the deposits. Further, the operation for placing the ports of the pipes of the manifold in the engine in the vicinity of the deposits can be performed only by those having enough experiences and skill.
Accordingly, it is an object of the invention to provide an easily operable method for clearing the internal parts of gasoline engines.